The X-ray Talbot interference method is an X-ray imaging method utilizing the Talbot effect. With an application of X rays to a diffraction grating, interference patterns, which are called “self-images”, are generated at a specific distance from the diffraction grating. When a specimen is placed between an X-ray source and a detector, the phase of the X rays is changed because of the presence of the specimen. Accordingly, the interference patterns having phase information concerning the specimen are detected, from which phase images of the specimen can be obtained.
It is necessary that X rays used in the Talbot interference method exhibit spatial-coherency. Spatial-coherency increases as the size of an X-ray source decreases. High-intensity X rays are also necessary in this interference method in order to increase the luminance of resulting images and to shorten the exposure time for a specimen.
Accordingly, in order to secure both X-ray spatial-coherency and X-ray intensity, a Talbot interference method performed by using an X-ray source which generates a plurality of narrow X-ray beams has been proposed.
NPL 1 discloses an X-ray source that generates a plurality of X-ray beams by irradiating a target provided with narrow grooves with electron beams. This X-ray source includes surfaces on the target from which X rays are emitted (hereinafter referred to as the “X-ray emitting surfaces” or more simply referred to as the “emitting surfaces”). By utilizing X-ray beams emitted in the oblique direction with respect to the X-ray emitting surfaces, the X-ray dosage per unit area is increased compared with a case where X-ray beams are emitted perpendicularly with respect to the X-ray emitting surfaces.
PTL 1 also discloses an X-ray source that can increase the X-ray dosage per unit area by irradiating a target provided with grooves with electron beams.